Coal Facts - Coal - Coal Mining

Coal Facts

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  • The United States produces over 1 billion tons or about 35% of the world’s coal supply – second only to that of China.
  • Coal generates more than half of the electricity used in the United States.
  • U.S. coal deposits contain more energy than that of all the world’s oil reserves.
  • The United States has more than a 250-year supply of coal if it continues using coal at the same rate at which it uses coal today.
  • Each person in the United States uses 3.8 tons of coal each year.
  • More than 2 million acres of mined lands have been reclaimed over the past 20 years – that’s an area larger than the state of Delaware.
  • The average coal miner is 42 years old and has 20 years of experience.
  • Wyoming is the top coal producing state producing about 390 million tons in 2004. Montana is the state with the most coal reserves of about 120 billion tons.
  • Coal ash is used as filler for tennis rackets, golf balls, and linoleum.
  • Texas is the top coal consuming state using about 100 million tons each year.

 

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Coal

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The United States produces about 35% of the world’s coal, more than any other country, and has more than 250 billion tons of recoverable coal, enough to last for hundreds of years.

Coal is essential, as it is used to generate more than half of all the electricity produced in the U.S. It’s also used as a basic energy source in many industries, including steel, as well as cement and paper. It’s also used as a heating fuel. Coal is good for the economy too as coal production provides thousands of jobs in exploration, mining, the supply of products and services, transportation and a whole host of other support jobs.

Coal is available as there is enough to last over 250 years. Many U.S. coalbeds are close to the earth’s surface and modern mining methods allows easy reach of most of our coal reserves.

Greater use of coal will help the U.S. become more self sufficient in energy. In addition to its use as a solid fuel, coal can be converted to gas to replace expensive imported fuels. Consumers also benefit because coal is an economical fuel. With expanded clean coal use, coal can help solve our energy problems. Like gas and oil, coal is a fossil fuel.

Coal was formed by vegetation growing in swamps which covered many parts of America about 300 million years ago. The vegetation absorbed and stored the sun’s energy. Peat deposits were built up as vast amounts of vegetation died and accumulated at the bottom of the swamps to form spongy brown materials. Geological forces buried the peat deep under the surface of the earth. There the layers of peat were further compacted by pressure and heat. The coal was formed from the compressed peat after millions of years under the earth’s surface. The greater the heat and pressure, the harder the coal.

There are four major types of coal. Coal is classified by hardness and the harder the coal, the less moisture it contains and the more efficient it is as fuel. Lignite (softest coal) contains a lot of moisture. It’s brownish black and crumbles easily. It’s mainly used at electricity generating plants. Bituminous (medium hard coal) contains very little moisture and is high heat value. It’s used to generate electricity and to make coke use in the steel industry. Sub-bituminous (medium soft coal) has much less moisture than lignite and is used mostly to produce steam for electricity generation. Anthracite (hardest coal) has a very high heat value burning slowly and making a good home heating fuel.

There are four major uses of coal in the U.S. Electric power generating plants burn coal to make steam. The steam turns turbines which generate electricity. Electric utility companies use about 90% of coal mined in the U.S. Coal is also used for industry, such as concrete and paper, and ingredients of coal, such as methanol and ethylene are used in making plastics, tires, synthetic fibers, fertilizers, and medicines. Coal is also used for making steel. It is baked in hot furnaces to make coke, which is used to smelt iron ore in the steelmaking process. The carbon in coal gives steel the strength and versatility for products such as bridges, buildings, and automobiles. Coal is also exported to Western Europe, Canada, and Japan.

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Coal Mining

There are two basic ways to mine coal. Surface mining is used when coal is found close to the surface or on hillsides. This is a safe and economical method used for over half of the coal mining in the U.S. Underground or deep mining is used to extract coal lying deep beneath the surface or on seams exposed on hillsides. Extensive safety precautions are taken to protect miners. Modern machinery has made deep mining safer and faster than ever before. Deep mining is carried out by either continuous mining or longwall mining.

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Caterpillar DraglineSurface Mining

This method of mining involves removing the overburden with heavy earth moving equipment, scooping out the coal, replacing the excavated soil and reestablishing vegetation and plant life, a process known as reclamation. It accounts for about 60% of total U.S. coal production.

A large surface mine, such as those found in the western U.S. can be three miles long and a mile wide. The mine is always on the move with mining take place at one location and reclamation occurring at another.

Modern surface mining is as much a land reclamation process as it is a means of extracting coal. Reclaimed sites are returned to many productive uses such as recreation areas, golf courses, wildlife preserves, parks, farms, wetlands, housing developments, and pastures.

Continuous Mining

Continuous miners were introduced in the late 1940s and use a large rotating steel drum equipped with tungston carbide steel, teeth or cutting bits. Continuous mining accounts for about 47% of total U.S. underground coal production.

Continuous miners operate in the room and pillar mining system in which a series of 18 to 20 foot wide rooms are driven in the coalbed with pillars or columns of coal left standing to help support the roof. The roof is also supported by roof bolts typically four to seven feet in length inserted into holes bored into the roof to bind the layers of strata together.

Longwall Mining

Originating in Europe, modern longwall mining in the U.S. began in 1960 and now accounts for 54% of total underground production. Longwall mining is highly productive and is the safest method of underground mining as the workers operate under the steel roof canopies of hydraulic shield supports.

A shearer machine fitted with two rotating cutting drums is hauled mechanically back and forth across the coal face cutting and loading the coal onto a heavy chain conveyor which delivers it onto a belt conveyor and out of the mine. The longwall panel or block is typically 1,000 feet wide and three or four miles long. The longwall shields advanced with the machine as mining proceeds and allows high levels of production and increased safety.


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